Multiple Relay Selection Improves the Performance of Wireless Communication Systems using MIMO
Abstract
Cognitive radio is an eminent technology that has been deployed in multiple communication systems in recent times. As in case of any communication system, the performance can be analyzed purely on the basis of transmitter and receiver. But it can be further enhanced by introducing relay concepts into the system. In a primary network, the data transmission takes place through a licensed channel. But at times the spectrum is not properly utilized and at that instant the secondary network comes into the picture, which takes care such that the efficiency of the spectrum shouldn’t be wasted. The secondary network consists of ST (Secondary Transmitter), SD (Secondary Destination) and Eavesdroppers. Here in the endeavor the main focus lies on the secondary network operations. The throughput of the network can be abruptly increased by introducing relays. To increase the overall system ability MIMO and OFDM techniques were implemented. The comparative analysis of the system with the single, multiple relays and the traditional direct transmission schemes has been done in order to analyze the system’s performance.
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Introduction
In any communication system, the client mainly concentrates on the security features. Because of the extremely attractive privacy settings, cognitive radio system has grabbed the attentions of the researchers. Even though an appreciable work has carried out regarding cognitive radio systems, due to its dynamic behavior the data is being accessed by the unauthorized users. The data loss occurs during the following phases: Spectrum sensing, Spectrum sharing, Spectrum mobility and Spectrum management. A lot of work involved in order to make sure that the CR environment is free from primary user emulation against denial of service and eavesdropper. The confidential transmission of data can be achieved by using traditional cryptographic methods at an expense of additional computational complexities. But still the existing cryptography methodology is not good enough to provide high accuracy and reliable security features to the system.
In the ISO-OSI layers, network layer is responsible for providing the security measures for the data to be transmitted. In addition to that, the security through the physical layer is inherited to provide excess security capabilities. Inculcation of security features in the physical layer is a sophisticated methodology which minimizes the data decryption by the eavesdroppers.
Conclusion
In this paper, we propose relay selection schemes for a cognitive radio network consisting of ST (secondary transmitter), SD (secondary destination), and multiple SR (secondary relays) communicating in the presence of eaves dropper. We have examined the performance of the SRS (Single Relay Selection) and MRS (Multiple Relay Selection) assisted secondary transmission along with traditional direct transmission.
To improve the transmission efficiency in cellular system where relays are installed, instead of simply amplifying and forwarding the received signal, relays are expected to have more coding capabilities to achieve higher data rates. We also observed that with the help of multiple relays in asynchronous case compared to synchronous single relay case we are getting more throughput rate with the decode and forward (DF) relays where the source and relay transmit in the same channel. This works show that the proposed SRS and MRS schemes out-perform the conventional direct transmission. With the increase in the number of SR’s, the performance of the system improves significantly.